Pascual Jordan



Ernst Pascual Jordan (18 October 1902 – 31 July 1980) was a German theoretical and mathematical physicist who made significant contributions to quantum mechanics and quantum field theory. He contributed much to the mathematical form of matrix mechanics, and developed canonical anticommutation relations for fermions. Jordan algebra is employed for and is still used in studying the mathematical and conceptual foundations of quantum theory, and has found other mathematical applications.

Jordan joined the Nazi Party in 1933, but did not follow the Deutsche Physik movement, which at the time rejected quantum physics developed by Albert Einstein and other Jewish physicists. After the Second World War, he entered politics as MP for the conservative CDU.

Quotes

 * In der Quantenphysik dagegen bedeutet jede Beobachtung einen Eingriff in das Beobachtete; eine Zustandsveränderung am Beobachteten ist auf Grund der quantenphysikalischen Naturgesetze mit dem Beobachtungsprozess zwangslaüfig verknüpft. Also nicht ein sowieso, unabhängig von diesem Experiment vorhandener Tatbestand wird wahrgenommen, sondern wir selber rufen die Tatbestände hervor (oder: nötigen sie in bestimmter Richtung zu einer Klärung), die dann zur Wahrnehmung gelangen.
 * In quantum physics, however, each observation implies an intervention in the observed. Because of the quantum physical laws of nature, a change of state of the observed is inevitably coupled to the observation process. So it's not a situation independent from the experiment that is observed, but we ourselves call forth the facts (or compel them to go in a certain direction to a disambiguation), that then become an observation.
 * Quantenmechanische Bemerkungen zur Biologie und Psychologie, Erkenntnis, Vol. 4 (1934). p. 228.